The prior art is already aware of various arrangements of crawler tractor track chain joints which utilize track pins and bushings and links mounted thereon, and the joint is commonly provided with a thrust member and also an elastomer type of seal. Thus the prior art track joints have the thrust member countering the mechanical force directed axially of the track pin, and they also have the seal members serving to keep dust and dirt and the like away from the articular joint provided between the track pin and the track bushing or link itself, in some instances.
My U.S. Pat. No. 3,948,574 discloses one arrangement of a track joint having the track pin and the bushing thereon and the spaced-apart pairs of track links and the elastomer seal therebetween. Further, U.S. Pat. Nos. 3,595,572 and 3,622,165 and 3,680,924 and 3,838,896, for examples, show track joints with combined metal rings and elastomer ring members disposed in the space between the links and the bushing and pin of the joint. In these examples, the metal ring itself is not utilized as a thrust member, and the seals are only of a singular nature and do not provide a dirt and dust and like sealing function on radially opposite dispositions of the rigid or metal ring itself. As such, the metal ring is provided mainly for supporting and presenting the elastomer seal, and it is not functionally utilized for serving as a thrust member or for serving as a seal itself.
U.S. Pat. Nos. 3,218,107 and 3,841,718 are further examples of prior art track joints with both metal rings and elastomer members disposed in the space described above, and, in these examples, the rigid or metal ring itself does extend in contact with both the outer link and the bushing member, and, as such, the metal rings of these examples are available as thrust members between the elements mentioned. However, the elastomer members are not related to the rigid or metal ring member described, and, as such, these examples are not displays or teachings of combined thrust members and two dirt-sealing members, with the dirt-sealing members serving to seal at least two different locations relative to the aforementioned space wherein the seal members are disposed.
Accordingly, it is an object of this invention to improve upon the prior art and to do so with a combined rigid type of thrust member with elastomer dirt-seal members related thereto and sealing the joint in at least two locations so that an optimum dirt-sealing efficiency can be effected. Further, the present invention accomplishes the aforementioned with a simplified type of combined thrust and sealing members, as mentioned, and it is also adaptable to a standard type of track joint arrangement having the usual space for receiving the aforementioned members.
Still further, it is an object and advantage of this invention to provide the aforementioned thrust and seal members in a track chain joint of a conventional nature and to have the seal members positioned and pressed into sealing relation during the assembly of the joint when the track links are pressed onto the track pin. As such, the counterbore in the track link acts as a guide and serves to align the seal members with the outer diameter of the bushing on which at least a portion of the seal members is positioned and effective. Still further, in accomplishing these objectives, the elastomer seal portions or members are compressed into a position and are related to the links and the bushing such that when there is a wearing of the elastomer members they will continue to perform full effectiveness in the sealing since the elastomer member is under compression and will simply continue to maintain sealing contact with the adjacent track joint element, even though a portion of the sealing member or members is worn down.
Additionally, the track joint of this invention accomplishes the aforementioned objectives and it does so with the elastomer portion of the members described above being cylindrical in configuration and being interposed between the two links of the joint and thus having a characteristic for torsional deflection in response to maximum articulation between the links. That is, when the track links are pivoted to at least a certain relative angle therebetween, then the cylindrical portion of the elastomer member will initially deflect or distort to accommodate the pivotal action, and eventually the thrust ring may be moved to slide relative to the outer link, and this is all permitted by virtue of the torsional characteristic described, and yet the dirt-sealing members retain their effectiveness while the full articulation of the joint is accomplished and is not restricted.
Other objects and advantages will become apparent upon reading the following description in light of the accompanying drawings: